It is known that photographic images which have a very high contrast can be formed using certain types of silver halides, and these methods of forming photographic images are used in the field of photomechanic process.
Conventionally, special developers known as lith developers have been used to achieve this objective. Lith developers contain only hydroquinone as the developing agent and sulfite which is employed as a preservative is used in the form of an adduct with formaldehyde and the free sulfite ion concentration is very low (generally not more than 0.1 mol/liter) so that infectious development characteristics are not impeded. Consequently, lith developers are very liable to be aerially oxidized and suffer from the serious disadvantage in that they cannot be stored for periods of more than 3 days.
Methods in which hydrazine derivatives are used as disclosed, for example, in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857 and 4,243,739 provide a means of obtaining high contrast photographic characteristics using a stable developer. With these methods, photographic characteristics of high photographic speed with ultrahigh contrast are obtained, moreover, since it is possible to add high concentrations of sulfite to the developer, the stability of the developer with respect to aerial oxidation is much greater than that of a lith developer.
These ultrahigh contrast systems in which hydrazine derivatives are used provide considerable economies to be made in the coated silver weight at high photographic speeds when compared with lith developer systems. Further, they also enable rapid processing to be achieved. However, they have a disadvantage in that it is difficult to achieve D.sub.max on exposure from the back side (the opposite side of the support to that on which the emulsion layer is located) of the photographic material.
A method of use is known in which photographs are taken from the back through the-support (the so-called lateral reversal method) with sensitive materials for camera use. When carrying out lateral reversal, the latent image is distributed with a bias toward the side closest to the support in the emulsion layer. On the other hand, the developer permeates from the surface on the emulsion layer side. Thus, development takes place from the surface and development is retarded in the part closest to the support. Consequently, the characteristic curve with lateral reversal is such that gamma for the intermediate tone shoulder portion is reduced and it is inevitably difficult to achieve D.sub.max. D.sub.max can be restored by increasing the silver coated weight but the effect of economizing considerably on the amount of silver, which is an advantage of the hydrazine high contrast system, is inevitably lost.
Furthermore, the amount of hydrazine derivative which is a nucleating agent added is sometimes increased to increase D.sub.max, and sometimes a development accelerator is used for this purpose. As a result, D.sub.max is increased when infectious development is strongly promoted, but black pepper (black spotting) tends to occur and there is sometimes a deterioration in screen dot reproduction characteristics.
These problems arise as a result of the fact that with lateral reversal the latent image is formed on the side closest to the support and they do not occur when the exposure is made from the emulsion surface side (with a so-called surface exposure).
Methods in which hydrazine derivatives are used and in which two or more types of emulsion are used are disclosed, for example, in JP-A-61-223734 and JP-A-63-46437 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"). However, in both cases use is made of a mixture of a coarse grain emulsion and a fine grain emulsion and this is different from the emulsion lamination of the present invention. Furthermore, these methods involve surface exposure and there is no disclosure of reverse exposure of the type used in the present invention.
JP-A-62-90646 and JP-A-62-8140 (both of which involve a lamination of a coarse grain emulsion layer and a fine grain emulsion layer), JP-A-63-15237 (in which a quinone scavenger is present in the intermediate layer with laminated emulsion layers), and JP-A-62-150343 (in which a high contrast emulsion layer and a low contrast emulsion layer are laminated) all involve surface exposure. There is no disclosure of a reverse exposure of the type used in the present invention which are disclosed in these published Japanese applications.